1. Technical Field
The present invention relates to a projector.
2. Related Art
As a light modulation device of a projector, there has been known a digital micromirror device (DMD) provided with a plurality of micromirrors, and capable of projecting an image corresponding to image data on a screen by the micromirrors each being driven in a time-divisional manner based on the image data. The DMD is a reflective image forming element, and controls the tilt direction of each of the micromirrors in accordance with the image information, and reflects the light from the light source toward the projection system to thereby form the image. Since the DMD is a reflective image forming element, it is necessary to input an illumination light beam from a direction oblique to the normal line of the image forming surface (the surface on which the micromirrors are arranged, namely a reflecting surface) of the DMD (see, e.g., JP-A-2004-279843).
Here, in the projector, in general, it is preferable to illuminate the image forming element with an illumination light beam having a light intensity distribution homogenous in the cross-section of the beam.
However, as described above, in the reflective light modulation device such as the DMD, since the illumination light beam is input from the direction oblique to the image forming surface, an uneven illuminance distribution appears on the image forming surface. Therefore, there is a problem that a luminance variation occurs in the projection image and the image quality of the projection image is degraded.